Internal coating and maximum operating temperature.

Internal coating and maximum operating temperature.

We have painted the internal surface of this tank with High Build Coaltar Epoxy 2 coat @ 200 micron DFT. Total 400 micron DFT. According to the paint data sheet the Immersion Temperature should not exceed 49 degree C.

I can see there is 13 degree C different.

What would be happen during operation of this Crude Oil Tank ? Is there any possibility melting of this Coaltar Epoxy ?

I know Coaltar Epoxy should not be applied for Crude Oil Tank. But this already happen.

RE: Internal coating and maximum operating temperature.

I hope in datasheet, it may be the recommended temperture. I would suggest to get the softening point, as well as maximum temp it can withstand, from the manufacturer. This is just to defend your current problem, as the job is already done.
Also, I dont believe coal tar epoxy cannot be used for crude tanks, untill unless there are aggressive chemicals included. I am still using coal tar on crude oil tanks with little problem. Can you help to give any references for your claim?

Cococa

RE: Internal coating and maximum operating temperature.

CocoCa, the data sheet states "immersion temperature should not exceed 49 C".

I have asked my paint subcontractor to get a letter from paint vendor stating " this high build coaltar epoxy still OK for 60 C operating temperature". To be honest I am very much doubt if the paint vendor will issue this letter.

I have called 2 paint vendor and they are not recommend coaltar epoxy for Crude Oil Tank due "causing cancer" issue more over this would be done in confined space.

The other vendor agree to use Coaltar Epoxy for Crude Oil tank but the operating temperature shall be below 49 C.

I have only 2 choices i.e. get letter from paint vendor or let us wait and see during operation.

RE: Internal coating and maximum operating temperature.

Fully cured epoxy will not "melt", but if the Tg temp of the cured epoxy coating is exceeded it does become soft and pliable. Brief exposure to a temperature 11degC above the continuous limit the manufacturer guarantees the epoxy coating for would not seem to present a problem.

To be sure you can conduct a test by heating a small section of the coated tank surface to the temperature expected for the amount of time required, and see if the coating degrades.

Lastly, I find it hard to believe an epoxy tank coating would not be good for temps in excess of 49degC (120degF). A steel tank exterior surface exposed to direct sun during summer in many parts of the world would easily get hotter than 49degC. In fact, the painted steel roof, hood and trunk surfaces of my car regularly get far hotter than 49degC when the car is parked in the sun on a summer day. The car's paint is polyurethane, and not epoxy based. But it probably gets up to 150degF without melting or peeling off the steel substrate.

RE: Internal coating and maximum operating temperature.

Good luck to you. But if you determine the coating to be unacceptable, it seems like it will be a huge amount of work to remove the deficient coating. So I'd imagine you would want to do everything possible to show the existing coating is acceptable for this application.

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